The American Cancer Society's new breast cancer screening guidelines, released in a recent issue of JAMA, state that women should start getting screened for the disease at the age of 45 instead of the previously recommended age of 40. The change is an update to their 2003 screening guidelines and was decided upon by a group of experts after examining new breast cancer studies and literature.

The reasons behind the change are multifold and can be confusing upon initial review. Here is a breakdown of the changes, and noted are some of the reasons behind the change.

The American Cancer Society suggests women should start receiving yearly mammograms at age 45. Women should continue receiving annual mammograms until they reach the age of 55. From age 55 on, women should receive screening biennially as long as they have a life expectancy of more than 10 years.

The guidelines also negate the need for manual breast exams. The group discovered that many women in their 40s who had mammograms received false positives, leading to unnecessary and sometimes painful biopsies and wasteful procedures. Women in their early 40s have more dense breasts, so tumors can be hard to detect, and tumors that are detected are sometimes harmless.

Women ages 40-44 who find the new guidelines too lax and prefer to be screened more often have the option to receive a mammogram annually, and women who have a family history of breast cancer should consult their doctor to determine how often they should be screened.

Of the 225,000 women diagnosed with breast cancer each year, about 40,000 ultimately die from the disease. But regular screening has been shown to reduce deaths in women aged 40 to 60, leaving many with questions about the reasoning behind the revised guidelines.

The new guidelines are attempting to reduce possible risks for patients while screening the most at-risk age groups. As women age, their risk for breast cancer grows exponentially. Women at age 40, the previously recommending screen age, have a 0.6 percent risk of developing breast cancer. Once a woman reaches 50, the chance of developing breast cancer doubles to 1.1 percent and continues to increase.

Although mammograms have been able to save the lives of many women by detecting the cancer in its early stages, new data suggests they may not be as effective as once believed. A recent study from Sweden concluded that breast cancer screenings, including mammograms, reduced deaths at a rate of 10 percent. Previous studies had found the screenings could reduce deaths by 20 to 25 percent.

The American Cancer Society is one of three organizations that have released breast cancer screening guidelines. The American College of Obstetricians and Gynecologists recommends regular mammograms at age 40, while the U.S. Preventative Task Force doesn't advocate regular screening until age 50.

Health insurance plans currently follow the guidelines laid out by the U.S. Preventative Task Force, and are required by health law to provide the preventative services recommended by the group to patients at no cost. Health insurers currently cover mammograms for women ages 40 to 50 when recommended by a doctor, which is not in line with the U.S. Preventative Task Force guideline. Now that another organization has raised the age for mammograms, health insurers may take note.

Physicians worry the competing guidelines may confuse their patients and prevent them from getting screened at all. In hopes of quelling the confusion, the American Cancer Society is scheduled to meet with the American College of Obstetricians and Gynecologists at a conference in January in hopes of reaching a consensus and creating a unified set of guidelines.

Many doctors are likely to wait for these more standardized guidelines to be released before putting them into practice, and some medical experts — like Harvard radiology professor Daniel Kopans — have stated they will continue to recommend annual screenings at age 40 in order to catch cancers as early as possible.